Riddle me this - Low and then Not so Low Water Output

I have yet to take the middleman out of the equation

Grohe Ladylux Faucet
Tapmaster

The *control* for the faucet is always on as the tapmaster controls the water outout.
With the ladylux on hot water, NO issues,
On mixed, NO issues

On cold only, I get a very slow flow.
Just simply moving the faucet handle to off and then back on, I get normal water pressure.
Once I release the *tapmaster pedal* - aka, no more water flow to faucet, and then press the pedal for cold water - Same symptoms.
If I simply move the handle on the faucet to on and then off, it's all good

Sounds like a check valve sticking.

Would it be the tapmaster or the faucet. Assume if I keep the pedal on, and just simply move the faucet from on to off to on, the faucet get's full flow

My guess it is the tapmaster.

http://www.tapmaster.ca/_pdf/Service Instructions.pdf

THANKS for the link Smooky.

I removed the plated, and the body, gave everything a good flushing and all is well !

Too bad they such pricey sunnv'b.
I have on order 1 more for my new remodeled laundry/mudroom.

It's been problem free for 4+ years...

My basement bathroom basin sometimes has low hot water flow. I think it is when the kitchen hot water is being used. Ideas?

Just a THUMBS up to Tapmaster.
Send me 2 new valves out 2nd day from Canada to the States.
Couldn't ask for better customer service turnaround and they deserve a public praise